This just started happening a few days ago. In game, when I mouse to the edge of the display where the secondary is, the cursor leaves the screen and moves about the secondary monitor. If I click while in this mode, it alt-tabs out of the game. I have to move back within the limits of the main monitor before I do anything. I have switched back and forth from windowed to full screen in whatever I'm playing, but it has no effect. the mouse still goes outside the main monitor. I've had this setup for over a month and this is the first time this has happened by accident. I finished up Bioshock Infinite on Friday without any sign of this happening. It doesn't affect BI even though other games are currently affected.

This has come up in the last few games I have played:SkyrimFallout NVStalker Call of Pripyat

I've resorted to using a program I dug up which limits the mouse to one screen, but it's imperfect. Last night in Skyrim, I inadvertantly tabbed out when I right-clicked in game, despite being nowhere near the border. plus, it's always on, so I have to turn it off after gaming. Much rather get this sorted out and back to normal.

No, haven't updated drivers. last let windows update on 3/20. Last thing I did before noticing this was install Call of Pripyat Complete. I didn't play much as the base game is buggier than expected and between that and the mod, it crashed 5 times, hard lockup. I nuked it after fighting it for an hour. not sure if it has any relevance but felt it warrants a mention.